Reactions of Hypervalent Iodine Reagents in Water

The development of aqueous-phase reactions using environmentally friendly reagents is one of the active fields in organic synthesis [3-5]. Several protocols for reactions of hypervalent iodine reagents in water and environmentally-friendly aqueous solvent systems have been developed. 

Tohma and coworkers have found that iodosylbenzene can be activated in aqueous solutions by addition of bromide salts to the reaction mixture [8,9], In particular, the oxidation of sulfides with iodosylbenzene in the presence of catalytic amounts of quaternary ammonium bromides selectively affords respective sulfoxides in high yields [8, 10]. The iodosylbenzene/KBr system in aqueous solution can be used for the 

Hypervalent Iodine Chemistry Preparation, Structure and Synthetic Applications of Polyvalent Iodine Compounds, First Edition. Viktor V. Zhdankin. 2014 John Wiley Sons, Ltd. Published 2014 by John Wiley Sons, Ltd. 

Activation of iodosylbenzene in the presence of KBr has been explained by the initial depolymerization of (PhIO) with the formation of a highly reactive intermediate PhI(Br)0 K+, which reacts with alcohols to yield the corresponding carbonyl compound with regeneration of KBr [11]. 

Zhu and Wei have reported a mild and highly efficient procedure for the oxidation of alcohols to the corresponding aldehydes or ketones using oligomeric iodosylbenzene sulfate 20 in water in the presence of 3-cyclodextrin, which serves as a biomimetic catalyst. The oxidation proceeded in water to afford aldehydes or ketones in excellent yields and high selectivity without overoxidation to carboxylic acids [41], 

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